Distinct Mid-Latitude Eurasian Rossby Wave Trains Preceding Strong and Weak Cold Surges in Southern China

Distinct Mid-Latitude Eurasian Rossby Wave Trains Preceding Strong and Weak Cold Surges in Southern China

Blog Article

This study investigates the large-scale circulation anomalies of strong and weak cold surges in southern China.Results show that the strong and weak surges are associated with a distinct Rossby wave train across Eurasia projecting onto the Scandinavia (SCAND) and Eurasian (EU) patterns.On one hand, the strong surge is preceded by a positive SCAND pattern and a transition of the EU pattern from its negative to positive phase.The corresponding wave train propagates southeastward from East Asia to the North Pacific.This is associated with dogbunny a strong intensification of the Siberian high, a deepened East Asian trough, and a sharp meridional pressure gradient between northern and southern China; these advect intense cold air masses from Siberia to southern China.

On the other hand, the weak surge is preceded by a negative SCAND pattern and a positive EU pattern.The corresponding wave train does not propagate from East Asia to the North Pacific.This wave train has a weak impact on the East Asian winter monsoon circulation and corresponds to weak att nighthawk hotspot cold air advections towards southern China.Overall, the intra-seasonal variation of the Eurasian teleconnection patterns is crucial for a comprehensive understanding of the cold surge in southern China.